Dec.
26, 2004 ó NOAA scientists acted quickly
when a warning was issued about the powerful undersea earthquake in
the Indian Ocean that triggered a devastating tsunami.
Within minutes following an alarm signaling the strong earthquake, the
NOAA Pacific Tsunami Warning
Center in Hawaii issued an information bulletin to nations in the
Pacific at 8:14 p.m. EST Saturday, indicating that a magnitude 8.0 earthquake
(later upgraded to magnitude 9.0) had occurred off the west coast of
Northern Sumatra, Indonesia. Because the earthquake, reported to be
one of the strongest in the world in the past 40 years, occurred in
the Indian Ocean, not the Pacific, there was no threat of a tsunami
to Hawaii, the West Coast of North America or to other coasts in the
Pacific Basin—the U.S. area of responsibility. (Click
NOAA image for larger view of Indonesia tsunami epicenter map. Click
here for high resolution version, which is a large file. Please
credit “NOAA.”)

Within
a few hours of learning of the tsunamis that killed thousands in Indonesia
Saturday night, Vasily
Titov, associate director of the Tsunami
Inundation Mapping Efforts, or TIME, at the NOAA Pacific Marine
Environmental Laboratory in Seattle, Wash., and his counterpart in Japan
had created preliminary model estimates of the event.

A tsunami
is a series of ocean waves generated by any rapid large-scale disturbance
of the sea water. Most tsunamis are generated by earthquakes, but they
may also be caused by volcanic eruptions, landslides, undersea slumps
or meteor impacts.

In 1963
the term "tsunami" was adopted internationally to describe
this natural phenomenon. A Japanese word, it is the combination of the
characters tsu (harbor) and nami (wave). They are often mistakenly called
“tidal waves.” However, the tides have nothing to do with
the formation of tsunamis.

The waves
radiate outward in all directions from the disturbance and can propagate
across entire ocean basins. For example, in 1960, an earthquake in Chile
caused a tsunami that swept across the Pacific to Japan. Tsunami waves
are distinguished from ordinary ocean waves by their great length between
peaks, often exceeding 100 miles in the deep ocean, and by the long
amount of time between these peaks, ranging from
five minutes to an hour.

While they
cannot be seen from the air, or felt aboard an ocean-going ship, tsunamis
can cause as great a loss of life and property as their other natural
disaster cousins—tornadoes and hurricanes.

The speed
at which tsunamis travel depends on the ocean depth. A tsunami can exceed
500 mph in the deep ocean but slows to 20 or 30 mph in the shallow water
near land. In less than 24 hours, a tsunami can cross the entire Pacific
Ocean.

A tsunami
warning system for the West Coast of the U.S. recently was awarded the
Gold Medal, the Department of Commerce’s highest award.

“As
with any natural hazard, education and warnings are essential,”
said Eddie N. Bernard, director of the NOAA
Pacific Marine Environmental Laboratory and first chairman of the
Tsunami Hazard Mitigation program, a multi-state, multi-agency effort.
“If people know what a tsunami is, what causes it, and what to
do in case it happens, fewer lives may be lost.”

Persons
caught in the path of a tsunami are at extreme risk from being crushed
or struck by debris, or drowning. Children and the elderly are particularly
at risk, as they often have less mobility, strength and endurance. Residents
are advised to seek higher ground or travel inland to get out of the
tsunami’s path.

Part of
NOAA’s mission is to understand changes in the Earth’s environment
and to provide public safety services.

The Pacific
Tsunami Warning Center was established in 1948, following the 1946 tsunami
in Hawaii that left more than 150 people dead. The PTWC serves as the
operational headquarters for the International
Tsunami Warning System in the Pacific, working closely with the
U.N. Intergovernmental
Oceanographic Commission International Coordination Group to provide
timely tsunami warnings to Pacific nations. In December 2001, the center
was renamed the Richard H. Hagemeyer Pacific Tsunami Warning Center
in honor of the late director of the NOAA National Weather Service Pacific
Region who ran the U.S. Tsunami Program for 19 years.

To increase
awareness about tsunamis, the NOAA National Weather Service began the
voluntary TsunamiReady
Community program that helps areas prepare for such events. To date,
there are 10 communities in Alaska, Washington, Oregon and California
that have met the TsunamiReady criteria.

The Coastal
Ocean Program at the NOAA
Ocean Service supported development of two tools for dealing with
Tsunami Hazards: model-based inundation maps and the deep ocean warning
system. Inundation maps, developed by the NOAA Pacific Marine Environmental
Laboratory, identify areas that are susceptible to flooding before a
tsunami occurs and are used to develop evacuation and land-use plans.
The NOAA Ocean Service also operates an extensive network of tide gauges
used by the warning centers to determine if a tsunami has been generated.

NOAA is
dedicated to enhancing economic security and national safety through
the prediction and research of weather and climate-related events and
providing environmental stewardship of the nationís coastal and marine
resources. NOAA is part of the U.S.
Department of Commerce.